Ok guys, sorry for trying to ask a serious question. I am middle-aged successful businessman and gun owner, helping a friend/business owner with a professional video shoot.

For those that want to be serious here, the plaster blocks are representing letters that need to "explode" for the purpose of their commercial or pictorial. (nowhere in final pictures/commercial product will there be a gun, or even a gunshot)

In a previous run, black powder was poured into drilled holes to create the effect. I am not sure if the black powder did not provide the entire effect they were looking for, or just trying something different, or no direct access to black powder. The trial here could be a complete failure, but was hoping that other firearm/ammunition enthusiasts might have some insight on what might work best.

This is an open forum, so feel free to mock the question and I will certainly be happy to spend my time elsewhere.